oil pressure sender

Thanks to all who responded to my question about the fire. I replaced the passenger oil line, as well as the heating duct and the car started fine. I let it run about 30 minutes and it reached operating temp fine (not to the half way mark on the oil temp guage). THe oil pressure sender was working.

Today I took it out of the garage to clean off the oil marks and when I cranked it I noticed the oil pressure guage was near zero. I rev'd the engine but the needle did not move. On recranking the needle went to 2 then quickly to near zero. After removing the wire to the oil pressure sender (which was in the fire) the reading went to above 5 as I expected. I only let the car run for a few minutes and the temp did rise on the guage but still in the lower boxed zone. The oil lines were warm as well as the oil filter. I am assuming the oil was circulating with this in mind. But how can I tell if the oil pump is working or my oil pressure sender is now shot? Is there a way to test the sender?

By the way, the only burnt wires were to the oil pressure sender and to the oil temp plug. I am for now concluding that I must have gotten something flamable on the air duct which caused the fire.

Thanks
mlyon

You can be sure that your oil pump is fine ... I don't think your engine would have run and warmed up sounding normal if the oil pump wasn't working!

The oil pressure sender should measure something in the 13-16 Ohm range with no pressure with the engine off. You can test it with either a digital or analog multimeter.

A quick test for the wiring to the oil pressure gauge is to turn the ignition on, but don't start the engine. With the sender lead 'open' the gauge should peg or read maximum, and with the lead grounded to the engine block, it should read zero.

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Warren Hall
1973 911S Targa

Thanks for the info. Mine reads around 5 ohms. Interesting thing though is that after the engine had completely dried after the wash, the oil pressure sender was functioning well again. I could not find any loose or frayed wires. How do you remove the sender? I guess it unscrews, but will a pair of pliers crush it?

thanks
mlyon

The 'zero' pressure resistance value of the senders may vary. Does the sender appear really charred, or just a little smokey from soot?

There is a hex on the underside of the 'bellows' part of the body. Don't remove by grabbing the body of the sender!

You may want to clean the connectors with a stainless steel 'toothbrush-style' brush. The female 1/4" quick-disconnect connector may have lost tension as the result of the fire. You can gently squeeze the sides to put a little tension back on those side rails ... with pliers.

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Warren Hall
1973 911S Targa

It is just sooty, but cleaned off now. The top where the electrical connection has some black stuff (for a better term)displacing it upward. But like I said before it is now working. Is it possible to get a wrench under the body of the sensor for removal?

Thanks
mlyon